Brush saws (sometimes called brushcutters) are used to cut brush or other vegetation from power line right of way areas, roadsides, forestry plantations, etc. In a typical brush saw, a drive motor and a cutting head are mounted at opposite ends of a support tube. A drive shaft is drivingly coupled through the support tube, between the drive motor and a pinion gear mechanism inside the cutting head. The pinion gear mechanism is in turn coupled to a drive gear spindle on which a cutting element such as a saw blade is rotatably mounted. Handlebars are provided on the support tube, between the drive motor and the cutter head. An operator grasps the handlebars and manipulates the brush saw to move the rotating saw blade through brush or other plant material which is to be cut. Controls on the handlebar enable the operator to stop the motor, vary the motor's speed, etc.
A commonly encountered problem is that stumps of cut plant material tend to resprout fresh shoots or buds which eventually mature, necessitating repetition of the cutting operation. Herbicide can be applied to the stumps to kill the cut plant or significantly retard its ability to resprout. It is often desirable to apply herbicide simultaneously with the cutting operation to avoid the time and expense of a separate herbicide application operation; and, because herbicides are more effective if applied immediately after cutting.
One relatively unsuccessful prior art technique is to dispense (drip) herbicide from a reservoir onto the upper surface of the brush saw's rotating saw blade. The difficulty with this technique is that little, if any, herbicide reaches the underside of the saw blade. Consequently, little, if any, herbicide is transferred to the cut material stumps, which is where the herbicide is required to prevent resprouting.
In another prior art technique, a herbicide reservoir is mounted on the underside of the brush saw's saw blade. Centrifugal force imposed on the reservoir as it rotates with the saw blade forces herbicide upwardly from the reservoir through a gasket onto the underside of the saw blade. Although this technique applies herbicide where it is needed (i.e. on the underside of the saw blade where the herbicide can be transferred to cut stumps) the somewhat bulky reservoir reduces the saw blade's effective cutting area. This technique also does not allow the operator to monitor or continually control the rate at which herbicide is dispensed while the brush saw is operating. Moreover, despite the reservoir's bulk, it contains a limited amount of herbicide. This necessitates more frequent stoppage of the brush saw so that the reservoir can be refilled, thus increasing the risk of herbicide spillage.
This invention addresses the shortcomings of the prior art.